Another document that used to be posted here, and was removed, is back by popular request. This document is the original PDF written to explain action sequences. It is about the only place a person can read about the original intent with action sequences, and it gives great insight into what the contract is that actions and the action sequence obeys. This is an immensely useful document if you need to build complex action sequences.

It would be great to extract the useful bits of this PDF and turn it into wiki doc.